A BROAD COALITION OF DONORS -- including casino giant MGM, Delta Airlines, a Washington nightclub and thousands of individuals across the country -- together gave nearly $6 million to the campaign to legalize same-sex marriage in Maryland, providing a financial advantage that supporters say was critical to the effort's success.

Marylanders for Marriage Equality, the main group working for approval of Question 6 on this month's ballot, raised $5.9 million -- more than twice as much as opponents of the measure, according to campaign finance reports filed this week. The money paid, in part, for a stream of television ads credited with helping to build support for the measure.

Voters approved the law 52 percent to 48 percent, and marriage certificates will be issued to same-sex couples in January.

"Donations came from a cacophony of places," said Fred Sainz, a spokesman for the Human Rights Campaign, a national gay-rights group that helped in Maryland. "Small donors. Donors via mail. Donors via the Internet. Our opponents do not have that momentum."

Supporters of the measure reported nearly 15,000 checks from individuals and organizations. Opponents drew a fraction of that, with about 2,300 donations. Each side received some six-figure checks, but proponents relied less heavily on large gifts. The average contribution on behalf of gay marriage was $402, while the average check from opponents was $1,037.

The large number of contributions -- on both sides -- distinguishes Question 6 from the gambling expansion measure also on the Maryland ballot. In that case, two huge casino companies with a financial stake in the outcome funded most of a $93 million battle, won by supporters of expansion. It was the most expensive political campaign in Maryland history. Unlike contributions to candidates for office, gifts to ballot campaigns are not limited by law.

All of the state's ballot committees were required to file their final campaign spending reports Tuesday night.

Supporters of the same-sex marriage measure raised almost half their money from Maryland donors -- with thousands of small house parties held nightly in September and October. Opponents relied more heavily on out-of-state giving, with 30 percent of their funds coming from the Free State.

"We knew that we were going to have to do a lot of this on our own," said Josh Levin, campaign manager for Marylanders for Marriage Equality. "We went out with an eye on developing the donor base in the state -- reaching out to folks who had a personal interest -- and did very well that way."

Frank Schubert, a consultant who managed the campaign against legalization of same-sex marriage in Maryland and three other states, blamed the fundraising gap on what he called a "sustained campaign of intimidation and harassment" against those who support "true marriage."

Contributors in support of same-sex marriage included Baltimore lawyer Peter Angelos, who gave $50,000. Angelos drew national attention for his contributions in this year's election, donating $1.5 million to support President Barack Obama and other Democratic lawmakers.

MGM Entertainment, which hopes to build a casino in Prince George's County, gave $75,000 to support same-sex marriage in Maryland. A spokesman for the company described the check as a "modest contribution" and noted that MGM has given previously to gay-rights causes.

The 9:30 Club, a concert venue in Washington, contributed $25,000 in support of the measure. The owners also held a fundraiser in September featuring "American Idol" star Adam Lambert.

"Although we historically don't get involved in political causes, I cannot stand by and watch discrimination be disguised as politics," said co-owner Seth Hurwitz.

Delta Airlines gave $1,000. Ebay, the auction website, sent $2,000 -- a spokeswoman said the check was "consistent with our core values of nondiscrimination, diversity and inclusion."

The Maryland-based biotech firm United Therapeutics Corp. gave $100,000. The company's founder, Martine Rothblatt, is transgendered.

Several unions contributed big dollars in support of the measure. The Service Employees International Union gave $200,000. The American Federation of State, County, and Municipal Employees and the American Federation of Teachers gave $100,000 each.

Politicians also offered support, with Rep. Chris Van Hollen giving by far the most. The Montgomery County Democrat wrote a $30,000 check from his Van Hollen for Congress account. Gov. Martin O'Malley, who sponsored the same-sex marriage legislation in Annapolis, gave $1,000 from his new superPAC. Many of the House and Senate co-sponsors of the legislation also donated.

Top Annapolis lobbyists and key staff members contributed, too, underscoring the deep personal support the same-sex measure had from the state's political elite. Checks came from top aides of O'Malley and House Speaker Michael E. Busch and from those of Senate President Thomas V. Mike Miller, who voted against the measure in the Senate.

State Sen. Bryan Simonaire was among the few Maryland lawmakers who donated to the effort opposing the measure. The Anne Arundel Republican was a leading opponent of the same-sex marriage measure when it was before the state legislature this year.

National advocacy groups contributed heavily on each side. The Human Rights Campaign donated $1.1 million to the effort to pass the measure. The National Organization for Marriage gave $1.2 million to the Maryland Marriage Alliance, which opposed Question 6.

Major contributions for opponents came from Roman Catholic groups, including $350,000 from the Knights of Columbus and dioceses in Arlington, Va., and Wheeling, W.Va.

William E. Lori, the Archbishop of Baltimore, gave $2,000 from his personal account. He gave "as a citizen of Maryland, a taxpayer and a believer in upholding marriage as between one man and one woman," said spokesman Sean Caine.

The donations by those who opposed the measure were not enough to get their message out, said the Rev. Derek McCoy, head of the Maryland Marriage Alliance. "A little bit more money, for sure we would have won," he said.

He said the national donor base was spread too thin because of gay marriage-related initiatives in three other states. He said his group's message was drowned out by ads for the other ballot questions in Maryland and that his side faced a formidable opponent in O'Malley.

"The governor was behind it," McCoy said, referring to the campaign in behalf of the law, a top O'Malley priority in Annapolis. "He did fundraising calls. He was calling people."

The total raised -- about $8.3 million by the main groups on both sides of the marriage issue -- paled in comparison with that spent by the opposing sides of the gambling expansion measure. That question attracted more than $93 million, mostly from two warring casino companies. The total is more than was spent on the past four Maryland gubernatorial races combined

MGM put up $41 million to support the gambling expansion proposal, while Penn National Gaming -- which owns a West Virginia casino that stands to lose customers to Maryland -- spent $44 million to oppose it.

Supporters of Maryland's Dream Act, a measure giving illegal immigrants access to lower in-state tuition, raised $1.7 million in their successful effort. The measure, Question 4, passed with nearly 60 percent of the vote and drew no formal opposition.

Contributors in support included Domino Foods, the Baltimore-based sugar company, which gave $100,000.

Stu FitzGibbon, the company's refinery manager, said: "In a nation of immigrants and a company that has grown in that tradition, we believe that an education is the one thing we give our children that cannot be taken away."

annie.linskey@baltsun.com

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Baltimore Sun reporter Michael Dresser contributed to this article.

Donor database

To search a database of donors on either side of the same-sex marriage debate, go to http://data.baltimoresun.com/marriage-donors/ ___